1. Field of the Invention
This invention relates to a method, apparatus and article enabling quickly and more easily cutting, breaking and installing building sheets, and more particularly, to building sheets having a surface groove system to guide a cutter without the need for a straight edge.
2. Description of the Related Art
Building sheets made of fiber cement and other materials are often used as backerboards for floors, countertops, walls, etc. For instance, backerboards for ceramic tiles are used for countertops to provide the water resistant, relatively rigid, dimensionally-stable foundation over which the tile is bonded during the installation. Conventionally, the backerboard is laid over an exterior grade sheet of plywood xc2xd to 1 inch thick and adhered thereto using an adhesive such as a dry-set portland cement mortar or latex-modified portland cement mortar thinset. The backerboard is also fastened to the plywood subfloor using nails or screws. Once the backerboard is in place, ceramic tile is laid over the backerboard and adhered thereto using a modified thinset or other suitable tile adhesives. Backerboards are installed in a similar manner for a number of other applications, such as tile backer for floor installations and wallboard installations where the material is installed direct to stud or exterior sheathing or paneling applications.
For these and other applications, building sheets must generally be sized and cut to an appropriate dimension for installation. For instance, tile backerboards must be appropriately sized and cut before placement over plywood subfloor. This can be a time consuming and labor-intensive process, requiring a number of different tools and great precision to size and cut a board to the desired dimension. Cutting of a backerboard typically requires using a straight edge and scoring knife to score the backerboard on one side, and then snapping the backerboard up against the edge of the straight edge to break the board along the score mark. It is often difficult (particularly for long cuts) to hold the straight edge in a fixed relationship to the material with one hand, and perform the scoring or cutting with the other hand. Resultant slippage can reduce the accuracy of the resulting cut. Alternatively, a circular saw with a carbide tipped blade or shears have also been used to cut backerboards.
To assist in determining a desired cut location, backerboards have been known to contain marker locations, for example markers 6 inches apart marked in ink, to indicate fastening locations for nails or drills. These markers can also provide a visual aid to enable a cutter to more easily locate a desired cutting location. U.S. Pat. No. 5,673,489 to Robell describes a gridded measurement system for construction materials such as wallboards wherein a plurality of horizontal and vertical unit measurement markings are positioned around the perimeter of the construction material surface to provide quick dimensional reference for sizing of the construction material. The construction material surface is filled with horizontal and vertical grid markings between the numbered unit measurement markings.
Construction boards with markings as described above, though generally assisting in visualizing cut locations, still do not significantly decrease the time and labor for installation. This is due in part to the fact that boards with markings still require the use of a straight edge or other tool to guide a cut mark across the board.
Accordingly, what is needed is a method and apparatus for reducing the time and improving the efficiency of installing building sheets such as backerboards, and more particularly, a building sheet that accomplishes some or all of these and other needs.
Briefly stated, the preferred embodiments of the present invention describe building sheets with a plurality of grooves indented into a surface of the building sheet to provide a guide for cutting the building sheet along the grooves. Preferably, the grooves are arranged in a regularly repeating pattern and are spaced apart by a standard unit of measurement in order for a cutter to accurately size the building sheet to a precise dimension. A simple carbide-tip scoring knife, such as supplied by Superior Featherweight Tools Company, Industry, Calif. is preferably used to score the sheet along the grooves, without the need for a straight edge, and the sheet is broken by simply bending the sheet along the score mark. The grooves are preferably provided at a depth into the surface of the sheet such that they do not substantially decrease the strength of the sheet or affect off-groove scoring and snapping. The design of the grooves is such that a score mark can be made between, across, or on a diagonal to the grooves and the material snaps so that the line of breakage follows the score mark and not the line of the nearby grooves.
Other indentations may also be provided into the surface of the building sheet. For instance, in one preferred embodiment, fastener indent areas may be provided at regularly spaced increments to receive nails or other fasteners. These indent areas allow the fastener to be inserted through the sheet with the head of the fastener being nailed or screwed flat or below the surface of the sheet. Edge markers may be indented along the edges of the sheet to further indicate desired measurement increments. Optionally, edges may be grooved, flat or set down. Set down areas at the edges of the sheet provide an area for nails, adhesives and joining tape to be placed onto the sheet without protruding above the surface of the sheet.
Thus, in one aspect of the present invention, a building sheet is provided. The sheet comprises a substantially flat board having a front surface and a back surface and a thickness defined there between. At least one surface groove is formed into one of the front surface and back surface. The groove defines a line of cutting adapted to guide a knifepoint across at least a portion of the board.
In another aspect of the present invention, the building sheet comprises a substantially flat board having a top edge, a bottom edge and opposing side edges, and opposing faces defined between the edges of the board. A surface grid system is provided on at least one of the opposing faces, the surface grid system including a plurality of cutting grooves indented into the face of the board that extend substantially across the face of the board in straight lines. The grooves are arranged in parallel and perpendicular to the edges of the board or to one another, and are capable of receiving a score mark for cutting and breaking the board.
In another aspect of the present invention, the building sheet comprises a substantially flat board having a front surface and a back surface and a top edge, bottom edge and opposing side edges. The board has a thickness defined between the front surface and back surface. At least one set down area is indented into one of said front surface and back surface. The at least one set down area is adapted to receive a fastener therein. In one embodiment, the at least one set down area includes a plurality of fastener guides arranged in a regularly repeating pattern across the surface of the board. In another embodiment, the at least one set down area includes an edge set down area adapted to receive a reinforcing tape therein.
In another aspect of the present invention, a building sheet construction is provided. This construction comprises a foundation layer having a front surface and a back surface, and a substantially flat board having a front surface and a back surface overlying the foundation layer. The back surface of the board overlies the front surface of the foundation layer. The front surface of the board has at least one preformed indentation into the surface thereof. At least one fastener having a head extends through the board into the foundation layer, wherein the fastener extends through an indentation such that the head of the fastener lies at or below the front surface of the foundation layer.
In another aspect of the present invention, a building sheet comprises a substantially flat board having opposing surfaces, and a plurality of indentations provided into at least one of said opposing surfaces. The board has a bending strength that has been reduced by no more than about 20%, more preferably about 10%, and even more preferably about 5% below than the bending strength of the same board without the plurality of indentations.
In another aspect of the present invention, a method of cutting a building sheet is provided. The building sheet is scored at a desired location on a surface of the sheet, the sheet having at least one cutting groove formed into the sheet. The scoring of the sheet forms a score mark in the surface. The sheet is bent along the score mark to break the sheet. In one embodiment, the sheet is scored such that the score mark lies within and substantially along a cutting groove. In another embodiment, the sheet is scored such that the score mark lies substantially outside of a cutting groove.